Liquid gas storage system



Sept. ,-1, 1970 RQ E. PEcK 3,526,095 Y LIQUID GAS STORAGE SYSTEM l FiledJuly 24, 1969 2 she'etsfsneet 1 BY 62 mmglfwm ATTORNEY INVENTOR RALPH E.PECK ATTORNEYS Sept. 1, 1970 Filed July 24, 1969 .1.r.....i f. .J

United States Patent O 3,526,095 LIQUID GAS STORAGE SYSTEM Ralph E.Peck, W. 34th St., Chicago, Ill. 60616 Continuation-in-part ofapplication Ser. No. 739,520, June 24, 1968. This application July 24,1969, Ser. N0. 845,940

Int. Cl. B65g 5/00 U.S. Cl. 61-.5 17 Claims ABSTRACT OF THE DISCLOSURE Asystem and method for storing liquefied gases in chambers. The walls ofthe chamber are coated with a petroleum fraction which is at leastpartly a liquid at rom temperature, and which boils at temperaturesbelow levels which would obtain petroleum oils. The petroleum fractionmay be a mixture of such liquid hydrocarbons and heavier hydrocarbonsapplied to the walls of the chamber and solidified to a non-brittle,waxlike state after charging the chamber withL a liquefied gas havingtemperatures which are sufiiciently low to flexibly solidify saidpetroleum fraction.

This invention relates to a storage system for liquefied gases, and to amethod for conditioning chambers to store liquefied gases in an improvedmanner.

This application is a continuation-in-part of U.S. patent application,Ser. No. 739,520, filed June 24, 1968 by the applicant named herein, andnow abandoned.

Subterranean chambers of various formations have been employed forstoring liquefied gases such as liquefied natural gas, liquefiedpetroleum paraflins, anhydrous ammonia and other liquefied gases. Theart has been principally concerned with utilizing such undergroundstorage chambers for liquefied natural gas and for petroleum gases.

The use of the term chamber is intended to refer to above ground andbelow ground storage systems, as well as in-ground systems. Such systemsmay include tanks installed above ground, and tanks partially or totallywithin the ground, that is, inground tanks. The use of the termsubterranean chambers is intended to refer to various below groundstorage systems, such as naturally present caverns or vaults in saltformations, and excavations or mines such as strip or pit type mines.Such mines may be formed in various grou-nd formations which may bewater bearing, or impermeable shale or limestone formations.

A subject of concern in this art is the heat transfer or heat leak dueto fissures, cracks or other ruptures in the wall of the cavern orchamber. Heat leak is detrimental to retaining volumes of liquefiedgases originally deposited in the chambers. Such boiloff losses can beserious.

The art has recognized that means should be provided to seal theseruptures to present or reduce the boiloff losses due to heat leak. Manyattempts to seal such ruptures have involved complex or expensiveprocedures which, additionally, have not been characterized by thedegree of success which is desired by practitioners. One particularapproach which has presented some attraction utilizes the loWtemperature of a liquefied gas to freeze liquids into a solid form toseal the ruptures. Another approach involves freezing water which isnaturally present in ground formations, or freezing water which is addedto ground formations. This technique is not without problems because itis difficult to control the amounts of distribution of the Water itselfhas some walls of the chamber, and frozen water itself has someobjectionable features as a sealant.

Patented Sept. l, 1970 ICC It is accordingly one object of the inventiontoprovide a system and method for effectively sealing above ground,inground and below ground chambers by relatively simple and economicalmeans to provide improved storage.

Another important object is to provide a system and method wherebychambers are conditioned in an improved manner to provide improvedstorage means for liquefied gases, such as liquefied natural gas.

Yet another important object is to provide a system and method in whichimproved coatings, provided on the interior walls of a chamber, areparticular liquid petroleum fractions which can be conveniently providedas liquids and which can be easily and advantageously converted toeffective sealants by the low temperatures of liquefied gases.

A still another object is to provide a system and method whereby aheavier, viscous petroleum fraction of mixed hydrocarbons is used toprovide improved coatings for upright walls in a storage chamber, withor without porous thermal layers.

Still another important object is to provide a system and method wherebyparticular petroleum fractions are advantageously used to coat and sealthe interior Walls of a chamber by forming coating layers which are hardbut yet free from objectionable brittleness.

A still further object is to provide a system and method which includesporous thermal layers and solidified petroleum fractions in a chamber tothereby store liquefied gases with reduced boiloff losses from heatleak.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

Objects such as those recited are accomplished with the system andmethod of the present invention which, generally, contemplates coatingthe walls of a chamber with a petroleum fraction which includes at leastpartly a liquid at room temperature and atmospheric pressure, suchliquid boiling at temperatures below levels which would obtain petroleumoils in fractional ldistillations. The applied petroleum fraction issolidified to a non-brittle, wax-like state after charging the chamberwith a liquefied gas, which temperature is suliiciently low to hardensaid petroleum fraction.

For a fuller understanding of thewnature and objects of the invention,referenceshould be had to the following detailed description taken inconnection with the accompanying drawings in which:

FIG. l is a highly diagrammatic sectional view illustrating anunderground system for storing liquefied gases, and the method forproviding such a system;

FIG. 2 is a highly diagrammatic sectional view similar to FIG. l, butwhich illustrates an alternative embodiment of the storage system; and

FIG. 3 is a highly diagrammatic sectional view which illustrates analternative embodiment in which a petroleum fraction is in the form of aviscous mixture for better adherence to upright walls of a chamber.

For purposes of illustration, the description will make particularreference to conditioning underground chambers, but such descriptioncould likewise apply to various above ground and inground installations.

The invention generally provides for sealing the interior walls ofsubterranean chambers, by introducing a petroleum fraction into thechamber to coat the walls therewith. The petroleum fractions may be aneasily handled liquid hydrocarbons at room temperature which isthereafter solidified on the walls by low ambient ternperatures Withinthe chamber. The low temperatures are attained by the liquefied gasesintroduced into the chamber, which temperatures are preferably at leastabout -150 F. The particular petroleum fractions employed,

which are solidified to effectively seal the ruptures, are notcharacterized by features which would detract from the recommended usethereof. In particular, the solidified petroleum fraction has acharacteristic resembling that of a wax and is, therefore, non-brittle.A very hard coating would be `brittle and would be subject tosubstantial cracking which would understandably detract from theadvantages obtained in the sealing step.

In one form, the petroleum fraction is of the type that is a liquid atroom temperature and atmospheric pressure, but which is not an oil or aheavy or a viscous material. The heavier petroleum fractions alone donot operate in the preferred and advantageous manner. In general, theutilizable petroleum fractions boil between 70 F. and 600 F. Aparticularly useful petroleum fraction is gasoline which boils atatmospheric pressure between about 100 F. and 230 F.; and kerosene whichboils between about 350 F. and about 600 F. The petroleum hydrocarbonfractions obtained in later distillation steps, such as coal oil andlight lubricating oils, are characterized by a decrease in desirableproperties in the solidified state. Such undesirable properties increaseat an accelerated rate when the petroleum fraction becomes heavier, suchas the higher viscosity oils or residue oils.

The heavier and higher viscosity oils or residue oils, however, areusefully applied in admixture with the foregoing liquid hydrocarbonpetroleum fractions. Such a mixture is used to advantage particularly inapplication of the petroleum fraction to upright walls. The heavierhydrocarbon component imparts better retention of the mixture to uprightwalls, that is, walls positioned so that gravity tends to make materialsdeposited therein to fall. The lighter liquid hydrocarbons, such asgasoline, imparts desirable sealing properties to the mixture when themixture is solidified by the liquid gas. In the preferred practice, themixture is applied to the upright walls, and then the mixture is coveredwith a porous thermal or insulating layer, such as foamed urethane. Thethermal layer contributes to retaining the mixture on the wall and toimproving insulation of the chamber. After the liquid gas is introduced,such thermal layer tends to shrink, but the properties of the solidifiedmixture is sufficiently flexible to stay in the walls. Heavyhydrocarbons, as such, would become embrittled when solidified, and theresultant ruptures would seriously detract from the desired levels ofsealing.

The petroleum fraction mixture preferably contains a solid hydrocarbon,by which is meant, a material which pour point is preferably greaterthan room temperature, or about 68 F. A hydrocarbon of such viscosityprovides better retention following application to the upright walls.The liquid hydrocarbon has a boiling point range as previouslydescribed, namely, about 100 F.600 F., with the majority of componentscontaining no more than six carbons. The major portion of suchcomponents will generally be of the C-C6 type. It is preferred that suchliquid hydrocarbons remain a liquid at temperatures slightly below thetemperature of the liquid gas introduced into the chamber. For example,gasoline is a liquid at 240 F. but solidified when LNG, which boils at260 F., is introduced into the chamber.

The liquid hydrocarbon may be present in the mixture from about to about40% by weight. In general, a higher amount of a given liquid hydrocarbonis present if the chamber is made progressively more cold. Thetemperature of the chamber is determined, of course, by the boilingpoint of the liquid gas and the volume of liquid gas deposited in achamber, The mixture is, therefore, a combination of the heavierpetroleum fraction, preferably Solid, and the foregoing liquid petroleumfractions. It will be understood that the practitioner may utilizevarious combinations of the heavier hydrocarbons and the liquidhydrocarbons to attain advantages of the invention, although theforegoing types of combinations are better suited for application to theupright walls.

The liquefied gases which are introduced into the subterranean chambershave temperatures sufficiently low to solidify the described petroleumfractions. Liquefied natural gas or LNG boils at about 259 F., ethyleneboils at about 155 F. and propylene boils at about 54 F. It is thereforeseen that the liquefied gases have temperatures at least as low as about50 F. However, it is preferred to attain ambient temperatures within thechamber or about at least 150 F. to quickly and efficiently solidify thepetroleum fractions of the type described. To illustrate a particularembodiment, kerosene, which starts to boil at about 350 F., is aflowable liquid at room temperature and solidifies to the consistency ofwax at about 260 F. when liquefied natural gas is introduced into thesubterranean chamber.

The process of conditioning the subterranean chamber for storingliquefied gases provides that the selected petroleum fraction isintroduced into the chamber, and then applied against at least a majorarea of the internal walls of the chamber. The petroleum fraction, whichis a relatively economical material, may be introduced in a variety ofways, such as filling the cavern and then exhausting the excess liquidpetroleum fraction by suction pumps or the like. The interior walls ofthe chamber may also be coated by spraying the selected petroleumfraction in a pressurized stream against the Walls until such walls aredesirably coated. The mixture of heavier and liquid hydrocarbons may beapplied by troweling on the upright walls, heating to lower theviscosity and then spraying, and in still other ways.

The petroleum fraction which is applied to the walls is then solidifiedby intnoducing into the chamber the liquefied gas which will be storedin that chamber. The temperature o-f the liquefied gas is, of course,sufficiently low so that the ambient temperature within the chamber islow enough to solidify the petroleum fraction coated on the walls.Practitioners will appreciate that a more rapid solidification withlower ambient temperatures will be obtained by introducing igreatervolumes of the liquefied gas into chamber of a 'given volume. It will befurther appreciated that liquefied gases with lower boiling points needbe present in smaller volumes than liquefied gases having higher boilingpoints to attain a desired ambient temperature for solidification.

eReferrinlg to the diagrammatic representation of FIG. 1, a subterraneanchamber formed as a natural cavern is indicated at 10. A shaft 12communicates the chamber with the area above ground surface 14. Aconcrete superstructure 13 is shown closing the shaft opening. A line 16is shown for delivering a petroleum fraction, which is liquid at roomtemperature, under pressure to a spray head 18 which may deliver thepetroleum fraction in a circular `spray pattern. Such a spray head maybe rotatable to centrifugally eject streams or droplets of the petroleumfraction onto the walls 19 of the cavern. A box is shown at 20 forhousing means to raise and lower line !1\6 so that a pressurized streamof the petroleum fraction, which is discharged from the end of line 16,may coat upper and lower portions of the cavern walls. Valve means areshown at 22 to control the flow, and a pump is indicated at 24 todeliver the petroleum fraction from a source (not shown) at selectedpressure levels.

Liquefed natural gas is adapted to charge the cavern from a source 26through a line 27. Pump and valve means are shown at 28 and 29,respectively. The liquefied natural gas may be discharged or Withdrawnfrom the at least a portion of the walls thereof. Such a porous thermallayer will, of course, have insulating properties which advantageouslyhelp to retard heat transfer into the cavern. Such a porous thermallayer may be deposited in the cavern and impregnated with the liquidpetroleum fraction before introducing the liquefied gas to solidify thepetroleum fraction. The remaining portions of the cavern walls may thenbe coated in a variety of ways, followed by introducing theliquefiedrgas in sufficient volumes to lower the ambient temperature inthe chamber to solidify the petroleum fraction on the walls. The porousthermal layer may take many recognized forms and may include aggregatesof prefoamed polyurethane or polystyrene particles blown into andagainst the floor of said cavern as a roll or in a collapsedform, andthen extended against the floor of the cavern. Also, curable syntheticresin mixtures may be introduced as a fluid into the cavern and thencured in situ.

Referring to IFIG. 2, the subterranean chamber is shown as an excavatedstrip mine or pit 41, and the communication with the ground level 43 isindicated as the upper part 42 of the strip mine. A superstructure 44covers the shaft opening or the top of the strip mine. A petroleumfraction charging line 45- is shown with a spray head 46, box 47 tolower and raise the line valve control means `48 and pump 49, similarlyas in FIG. l. A liquefied natural gas line 50- conveys liquefied naturalgas from a reservoir 51. The line is provided with valve control meansi52 and pump 5,3.

A further line 54 conveys a curable synthetic resin mixture under theforce of a pump S5. The resin mixture is delivered from a mixingcontainer 56 which receives the fiowable resin from communicatingcontainer 57 and further receives a chemical hardener from anothercommunicating container 58. The resin may be an isocyanate and thehardener may be a diamine. The pot life mixture is dispensed upon thefloor of the strip mine, whereupon it cures to form a foamed porouslayer 60. If the foamed porous layer does not adhere to the oor of thestrip mine, or if a prefoamed synthetic layer is placed on the floor ofthe strip mine, anchoring weights such as gravel 61 is dropped throughthe communicating shaft to hold the porous thermal layer on the oor.

The porous thermal layer is then impregnated with the petroleumfraction, which impregnant is diagrammatically indicated as at 62. Thebottom of the strip mine is then flooded with the liquefied gas tosolidify the impregnant and partially cool the pit. The walls of thestrip mine are then coated with the petroleum fraction, after which, themine is charged with a liquefied natural gas 63. The cold ambienttemperature within the strip mine will then solidify the petroleumfraction into a waxlike coat 64 to efiiciently seal the cavern andprotect the deposited liquefied gas against undesirable boilolf lossesthrough heat leak.

FIG. 3 illustrates an embodiment wherein a petroleum fraction is amixture containing by weight of gasoline in a solid hydrocarbon whichhas a pour point at about 85 F. The mixture is applied to the uprightwalls of a pit mine. A source of liquid gas 70 is urged through pump 72and valve 74 through line 76 into the chamber. The floor or bottom wall77a and upright walls 77b of the chamber 77 are covered with thepetroleum fraction mixture 78 which may be applied by manual troweling,or by equivalent mechanical means. A thermal layer 80 is cut to fit thefloor and upright walls, and pressed against the mixture. The concretesuperstructure 82 is mounted with gas inlets and outlets and LNG isintroduced until a desired level 84 is deposited. The LNG solidifies thepetroleum fraction 78 which retains sufficient flexibility to provideimproved sealing. Such sealing is enhanced by the porous thermal layer80. Other means may be selected to introduce the mixture, such as anangularly extensible conduit with an extruder which may be positionedproximate to the walls. 'Ihe heavy mixture may be applied to the wallsby the extruder moving over substantially the total area of such walls.Further, the mixture may 4be heated to render same more owable, and thenintroduced through a conduit with an atixed spray head. The viscosity ofthe mixture will increase as it cools on the walls to enhance retentionthereof, particularly on upright walls.

It is required that the sealant not be solidified into a very hardphystical state because ruptures will develop in the coat as a result ofbrittleness. The prescribed petroleum fraction may be convenientlyhandled for application and also can be solidified to the desirednonbrittle state. If in a particular system or method, a given petroleumfraction tends to solidify to an undesirable degree of hardness, thenthe practitioner may add parafiins such as propane or butane to softenthe solidified petroleum fraction. The actual concentration of aparticular parain in a given petroleum fraction will depend on thedegree of hardness desired by the practitioner. The

practitioner will readily make such determination in view of the natureof the petroleum fraction employed, and the ambient cooling temperatureswhich are expected to be attained in the subterranean chamber. Theamount of the particular paraffin which will be added to a given volumeof a petroleum fraction may be readily determined on a small scale pilotlevel or in actual field conditions.

The advantages of the system and method may be illustrated byconsidering the filling of a cavern having a su'bstantailly cylindricalconfiguration, said cavern having a diameter of about 135 feet and adepth of about 180 feet. The walls of the chamber are covered with aliquid petroleum fraction and the floor of the chamber is provided witha porous thermal layer of about ten inches in thickness. The thermalconductivity of the ground formation may be considered as being about2.3 B.t.u. per hour, per foot. Adding liquefied natural gas to thechamber at the rate of about 18,000,000 cubic feet per day would lead tothe filling of the chamber in about 125 days. Maintaining the chamberfilled for about 110 days reduces the boiloff loss from about 7,500,000cubic feet per day to about 5,070,000 cubic feet per day. By the fourthyear, the boilolf loss falls to a level of about 3,700,000 cubic feetwhen maintaining the cavern at full levels. If the chamber is notconditioned according to the teachings of this invention, the chamber isnot expected to be filled within one year because of boilol loss. Ingeneral, the boilolf would increase several fold without thepretreatment or conditioning, say two to three times the foregoingestimated levels.

The invention may now be practiced in the various ways which will occurto practitioners, and all such practice is intended to comprise a partof the invention so long as it comes Within the terms of the appendedclaims which are given further meaning by the language of the precedingspecification.

What is claimed is:

1. A system wherein liquefied gas is storable in a chamber, said systemincluding a flexibly solidified petroleum fraction substantially coatingthe interior walls of said chamber said petroleum fraction at leastincluding a minor portion of a hydrocarbon which is a liquid at roomtemperature and at atmospheric pressure, said hydrocarbon liquid boilingat temperatures from about F. to about 600 F., and a charge of liquefiedgas in said chamber which provides an ambient temperature in the chambersufficiently low to have solidified said petroleum fraction.

2. A system as in claim 1 wherein the liquefied gas is liquefied naturalgas in an underground chamber.

3. A system as in claim 1 wherein the petroleum fraction is gasolineboiling from about 100 F. to about 230 F. at atmospheric pressure.

4. A system as in claim 1 wherein said petroleum fraction is keroseneboiling between about 350 F. to about 600 F. at atmospheric pressure.

5. A system as in claim 1 wherein said petroleum fraction is present asa solid layer over substantially the entire interior walls of thechamber, and said solid layer is maintained at the general consistencyof wax by ambient temperatures of at least about 150 F.

6. A system as in claim 1 wherein there is further included a porousthermal layer in proximate location to a portion of the interior Wallsof a subterranean chamber, and said porous thermal layer being chargedthroughout a substantial portion thereof with said solid petroleumfraction.

7. A system as in claim 1 wherein the petroleum fraction is a mixture ofa heavy hydrocarbon having a pour point greater than room temperature,and from about to about 40% by weight of a liquid hydrocarbon boilingbetween about 100 F. and 600 F.

8. A system as in claim 7 wherein said petroleum fraction mixture isapplied at least to the upright walls of the chamber, and furtherincluding a porous thermal layer covering said applied mixture.

9. A method for conditioning a chamber so that said chamber may be usedto store liquefied gases, including the steps of delivering a petroleumfraction into said chamber, applying said petroleum fraction to theinterior walls to substantially coat said walls, said petroleum fractionat least including a minor portion of a hydrocarbon which is a liquid atroom temperature and atmospheric pressure, said liquid hydrocarbonboiling at temperatures of about 100 F. to about 600 F., and chargingsaid chamber with a liqueiied gas having a temperature suiciently low toflexibly solidify said petroleum fraction and thereby seal said walls.

10. A method for conditioning a chamber as in claim 9 wherein the gas isliquefied natural gas in an underground chamber.

11. A method for conditioning a chamber as in claim 9 wherein thepetroleum fraction is entirely a liquid at room temperature andatmospheric pressure, said hydrocarbon fraction being applied tosubstantially the entire area of the chamber walls.

12. A method for conditioning a chamber as in claim 11 wherein saidpetroleum fraction is gasoline which 8 boils at atmospheric pressurefrom about F. to about 230 F.

13. A method for conditioning a chamber as in claim 11 wherein saidliquid petroleum fraction is kerosene boiling at atmospheric pressurefrom about 350 F. to about 600 F.

14. A method for conditioning a chamber as in claim 11 which furtherincludes the step of first depositing a porous thermal layer on thefloor of said chamber, impregnating said porous thermal layer with saidpetroleum fraction, delivering said petroleum fraction to coat anyremaining areas of the chamber walls, and then charging said chamberwith a liquefied gas to solidify the petroleum fraction in said porousthermal layer.

15. A method for conditioning a chamber as in claim 11 which furtherincludes applying said liquid petroleum fraction to at least a portionof the chamber walls, and then mounting a porous thermal layer to saidapplied petroleum fraction prior to charging said chamber with saidliqueed gas.

16. A method for conditioning a chamber as in claim 9 wherein saidpetroleum fraction is a mixture of a heavy hydrocarbon having a pourpoint greater than room temperature, and from about 10% to about 40% byweight of said liquid hydrocarbon, and wherein said mixture of heavyhydrocarbon and liquid hydrocarbon is applied to at least the uprightwalls ofthe chamber.

17. A method for conditioning a chamber as in claim 11 Which furtherincludes the step of covering said applied mixture With a porous thermallayer.

References Cited UNITED STATES PATENTS 3,205,665 9/1965 Van Horn 62-45 X3,344,607 l0/l967 Vignovich 62-45 X 3,407,606 10/1968 Khan et al 62-45 XROBERT A. OLEARY, Primary Examiner A. W. DAVIS, JR., Assistant ExaminerU.S. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,526,095 Dated September l, 1970 Inventor(s) Ralph E. Peck It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

LIQUID GAS STORAGE SYSTEM Ralph E. Peck, Chicago, Ill. assigner to GasDevelopments Corporation, Chicago, Ill., a corporation of Illinois FiledJuly 24 1969, Ser. No. 845,940 17 Claims.

SIGNED Mw NOV. 17,19YO

All:

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